It is a worrying time, especially the first time. It helps to remember that just because something can happen does nto mean iot absolutely will.
I've seen hens get chicks out of a ten feet high hay loft. Mama says jump and they do, then they run to her when they are on the ground. They are a lot tougher than many people think, but there is always the possibility that something could happen when they jump. I personally would not worry about 5 feet but I can't give you any guarantees that one won't get injured when it jumps.
Another possibility is that a chick may fall out of the nest before Mama is finished hatching. That is not good. Mama then has a tough choice. Does she leave the chick to its own devices or does she abandon the rest of her eggs ti take care of that chick? If you have a decent lip across the front of the nest, it is unlikely for a chick to accidentally fall out, but I don't know what your nest and the lip looks like.
Most of my broodies just take the chicks to a corner of the coop and keep them on the floor overnight. I have had a few that try to return to the nest at night. That nest is maybe 12" to 14" off the floor. Most of the chicks can jump up there if she calls them, but they will never make 5 feet. I always check around bedtime to make sure she has collected them all. Sometime I have to catch a couple an put them in with her for one or two nights. Sometimes she comes back off the nest and keeps them all on the floor.
I sometimes have a separate nest set up on the floor of the coop so they don't have to jump up to a nest. Sometimes Mama will use that nest and sometimes she takes then to a corner of the coop.
If you do move her, night is a great time, using as little light and commotion as possible. You might leave her locked in the nest for several hours so she cannot abandon it. Broodies go all day without getting off to eat, drink, and go poop. It's not cruel to imprison her on the nest for several waking hours to make sure she cannot leave.
Good luck!!!
